In communication using microwaves, parabola antennas or planar antennas with directivity are used. Particularly in recent years, planar antennas that can be installed in a space smaller than spaces where parabolic antennas are installed have been attracting attention.
Patent Literature 1 discloses a technique relating to a planar radar that can reduce the number of antenna elements (antenna units) while preventing sidelobe characteristics from deteriorating. In the planar radar disclosed in Patent Literature 1, the antenna units are arranged in a cross shape.
Patent Literature 2 discloses a technique relating to a planar antenna capable of achieving low sidelobe directional characteristics without lowering a gain.